Market demands have caused successive recent generations of data storage devices to be continually smaller but more capable. That is, consumers today want and get ever-greater storage capacity and processing speed in a smaller package. This dichotomy has been and will continue to be met by designers who factor in higher bit-areal storage densities, faster data transfer speeds, tighter transducer flying heights, and more robust mechanical components.
All these design factors make data storage devices more susceptible to vibration. Vibrations once conveniently ignored for being negligible must now be effectively managed to prevent perturbances that can render position-control systems ineffective due to track misregistration errors and servo tracking errors. For instance, the smaller and stiffer mechanical components in miniaturized assemblies have relatively higher natural frequencies, and as such are more sensitive to external excitation. Testing of such components requires more scrutiny of the modal frequency response in order to successfully design away from resonant frequencies that create such perturbances.
There are generally two categories of previously attempted solutions for measuring a data storage device component's modal frequency response. In the first, an impact hammer is used to excite the test object. In the second, a mechanical shaker device is used to excite the test object. The former disadvantageously does not provide a continuous and stable periodic excitation. The latter disadvantageously distorts the modal frequency response due to the mass loading associated with the requirement of attaching the shaker to the test object, and the fact that the excitation forces are transmitted through the attachment link. What is lacking in the art is an apparatus and method that provides free-state excitation for a modal frequency response analysis. It is to that improvement in the art that the claimed embodiments are directed.